Communication system



Nov. 11, 1930.

J. W HORTON COMMUNICA TION SYSTEM Filed NOV. 24, 1928 Ebtgh //V 5 N TOP J WHonraw,

A TTOPNEY Patented Nov. 11, 1930 UNITED STATES PATENT OFFICE JOSEPH w. HORTON,

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0F CAMBRIDGE, MASSACHUSETTS, ASSIGNOB TO INCOIFPORATEID, OF NEW YORK, N. Y., A OOBPO BATION OF NEW BELL TELEPHONE commumcarron sys'rm Application filed November 24, 1928. vSerial No. 321,589.

This invention relates to systems of communication, andimore particularly to systems for communicating with vehicles in motion as, for instance, railway trains.

One system for communicating between moving vehicles and a terminal station is disclosed in Patent 1,453,387 to H. A. Afiel, patented May 1, 1923. In this system a loop comprising a plurality of turns of wires,-1ocated on the vehicle, is inductively coupled with a line paralleling the vehicles right of way. Sufliciently close coupling quate transfer of energy is obtained, in this instance carrier frequencies being used. Aboard the vehicle there are connected to the loop a modulator and demodulator for transmitting and receiving signals, while similar sending and receiving stations are placed along the line for communicating therewith.

In such a system, because of the fact that the train moves from one station to another, a variable attenuation may occur in the strength of the signals being received from and transmitted to the stations along the line, causing the volume of the sound to gradually increase or decrease, depending upon whether the train is moving toward or away from a given station.

An ob]ect of this invention is to render the attenuation of the signals transmitted be tween a moving vehicle and the stations between which it is moving, constant, notwithstanding the motion of thevehicle withrespect to the stations.

In order to accomplish this object, a line is located parallel to the path of the movin vehicle and is inductively related to a pair of loops placed at right angles to each other on the vehicle in such a way as to make the coupling between the line and each loop vary with distance from train to station.

Each loop is connected to terminal apparatus on the train for communicating with a diiierent one of the terminal stations. In order to provide for constant attenuation not withstanding the increasing-or decreasing distance between the stations and the vehicle due to its motion, the plane of the wires comprisir the line strung along the track is rotated for adethrough an angle in nal station to the other, or between repeater points. The relation of the loops and the direction of rotation is such that as the train passes from one station to the other, the coupling between the line and the loop associated with ap aratus for communicating with the station rom which the train is moving is gradually increased, whereas the coupling between the other loop associated with apparatus for communicating with the station toward which the train is moving is decreased. Thus, the coupling between the respective loops line varies in accordance with the distance between the vehicle and the respective station with which the loops are associated. This scheme of providing an evenly varying coupling results in constant attenuation of the signals being transmitted between either station and its associated terminal apparatus aboard the vehicle. i

A better understanding of the invention may be had from the following'description together with the accompanying drawings, of which Fig. 1 shows a schematic view of the circuit embodying the invention and Fig. 2 shows curves representing the characteristics of the filters used in the circuit.

The apparatus and general layout of the system is similar fel patent referred to, and reference may be made to that patent for detail disclosure of various portions of the system.

Referring to Fig. 1 a vehicle 1 as, for example, a railroad train or other moving body is represented as t veling between two stations, which for convenience have been designated station A and station B. Paralleling the right of way and connectin stations A and B is a pair of conductors 2 and 3 which may be placed on poles or located in some convenient place adjacent the road bed. Aboard the vehicle 1 are two loops 4 and 5 consisting o a plurality of turns, the loops being located in planes perpendicular to each other and arranged so as to be inductively coupled with the line L.

Associated with the line L at stations A and B are terminal apparatus for passing from one .termito that disclosed in the Afline L comprising a aboard the vehicle and the speech range to be the type disclosed in U. S.

, An oscillator 14 sending signals to and receiving signals from the vehicle 1. Connected respectively to the loops'4 and 5 are terminal apparatus A jand B on thevehicle for" communicating respectively with the stations A and. B. In order to secure an adequate transfer of energybetween the line'L and the loops 4 and 5 relatively high frequencies are used. This is also desirable since it permits the communication between the stations A and B and the vehicle by using different carrier channels. i

At station A a low pass filter 6 and a high pass filter -7 are connected to the line L for discriminating between carrier'and voice frequencies, since it may be desirable to have both superimposed upon the line. The sending and receiving apparatus at this station is of a well-known type comprising a hybrid coil 8'fo17 aiding in separation of the incoming and outgoin signals intotheir respective channels. The hybrid coil terminates in a high pass filter,9 simulating the impedance o the high 10 for balancing the line.

Connecting with station A is an ordinary telephone line L carrying currents in the impressed on the modulator at station A or resulting from demodu lation of- Waves received at station A from the train. Line L mayextend to an ordinary telephone exchange where it may be connected to ordinary subscribers lines.

A hybrid coil 12 connected to the line L, serves the same purpose as the hybrid coil 8 and permits signals coming thereover to be transmitted to themodulator 13 which may be of any well-known type as, for instance, that disclosed in U. S. Patent 1,343,307 issued to John R. Carson on June 15, 1920. which may also be of any well-known type as, for instance, that disclosed in U. S. Patent 1,356,763 to R. V. L. Hartley, patented October 26, 1920 supplies the carrier frequency to the modulator 13. A modulated wave or a side band thereof is selected from the output of the modulator by the band-pass filter F which may be of Patent 1,227,113 to G. A. Campbell, patented May 22, 1917, and is transmitted to line L through the hybrid coil 8. Incoming signals from the line L from the terminal apparatus A aboard the vehicle are selected by the bandpass filter F which is similar to F5 although covering a different range of fre-' quencies, and transmitted to the demodulator 11 which may also be of any well-known type as, for instance, that disclosed in U. S. Patent 1,343,308 issued to John R. Carson on June 15, 1920. A reenforcing carried frequency is supplied to the demodulator 11 from 'an oscillator 15 similar to oscillator 14 for the purpose of demodulating the incomingcarrier band. The resultant signals in simultaneous pass filter 7 and a networkthe output of the demodulator are transmitted to the line L through the hybrid coil 12 to a suitable receiving circuit. Fig. 2 shows the relative positions of the frequency ranges transmitted by the band-pass filters F and F The terminal apparatus A connected to loop 4 aboard the vehicle is similar to that at station A and comprises the oscillation generators 16 and 17, modulator 18, demodulator 19,'and filters F and F properly connected for communication with station A. The mod-- carrier channels used for transmitting beand between A and The frequency bands, as F F F and F in Fig. 2 are those transmitted respectively by the band-pass filters F F F and F, at the terminal stations A, A B, B

As the line L passes from station A to B the plane of conductors 2 and 3 is rotated through an angle of Thus, for the purpose of illustration conductors 2 and 3 are represented as being in a horizontal plane in the vicinity of station A station A to station B the plane of the wires is gradually rotated until at station B the plane has acquired a vertical position. It will be un erstood, of course, that in practice a lon length of line is traversed before the entire 90 rotation takes place, and that intermediate the two poles shown on the drawing there would ordinarily be several miles of line with numerous other poles not shown. As has already been pointed out, the loops 4 and 5 are at right angles to each other. When vehicle 1 is near station Athe plane of loop 4 is nearly at right angles to the plane of the conductors 2 and 3 whereas the plane of loop 5 is nearly parallel to the station A to station B, the respective condi-] tions of coupling the conductors 2 until of the" loops 4 and 5 and 3 are gradually changed loop 4 has maximum 1 except that In passing from lot upon reaching station B the reverse con 1111310113 obtain, namely,

couplin and loop minimum coupling with constanttransmission equivalent between the con uctors 2 and 3. u said line and said transmission means, re-

7 In general, high frequencies such asthose ardless of the position of said moving used in this invention are subject to greater ody with respect to said terminals;

5 attenuation on the line than low frequencies. 2. In a s stem for communicating between For this reason during transmisison from a moving hody and a terminal from whic either station the energy of the signals which it is moving, a transmission line paralleling is available at any point along the conductors the route of said moving body, transmission 2 and 3 is less as the distance of the point from means on said body inductively related to m the-station transmitting the signa increases. said transmission line for the two-way trans- Sup ose, for instance, the vehicle 1 is movfer of energy therebetween, and means tov mg r0111 Sta lon A t a n B- If Station change the coupling between said line and A mm ni W h apparatus 1 in the said transmission means as a function of the vehicle 1, ordinarily the strength of the sigdistance of the moving body from the termi- 15 115118 lecelved at elthel A 1 would become nal toprovide substantially constant attenu- 3o weaker the greater the distance from the sendni f th energy lti f id t ihg h- Hewevelfa due the feet that way transfer regardless of the position of the eehphhg of the hne L Wlth the p 4 said moving body with respect to said termigradually increases as the vehicle moves L g a y from St as Pe'lllted out above 3. In a system for communicating between g5 the e 1h eflieleney of e g transfer a moving body and the terminal stations befrom the hhe t0 the p and vlee Verse h' 'tween which it is moving, a transmission line Pehsetes the gradual decrease 111 e 1 connecting said terminals-and paralleling the able energy result ng from the attenuation route f id moving body, t i i 25 on t e- In thls e level of the means on said body inductively related to received slgnals y be mamtamed p said transmission line for the two-way transat y e h fer of energy therebetween, the coupling be- Llkgwlse, eelhmuhleetleh between t tween said transmission line and said transtleh B and the Vehlele 1 as 1t 18 Passmg m mission means being a function of the dissiationfk to f analogous P tance of the moving body from the termition ex 1sts, since in passing from stationA naL I v to statlon'B the couplmg of the loop 5.w1th 4, In a system for communicating between conductors- 2 and decreases from maxlmum a moving body and the terminal stations beto mmimum causmg the efliclency of energy tween which it is moving, a transmission line i i' to decrease compensate 3 the for carrying the signal energy transmitted to increasing energy available as the vehicle apand received from Said body said transmis preaches Statlon sion line comprising a pair of conductors the means f i mvetmon commumca' plane of which is rotated throu h an angle tum can be i slmultaneously of 90 in traversing the distanceietween the tween a moving vehicle and two or more stastations 1 t omts relative t which it 15 5. In a system iorcommunicating between whl at Sam? i the energy level a moving body and a terminal station, a the slgnals 1s mtmtamed cnS.tant transmission line comprising a pair of wires wlthstandmg of the g connected to said station, a conducting loop 4 .Although thls lnventmn.has been 2? ed for receiving energy positioned on said body wlth reference to f em lment inductively coupled with said transmission thereof other embodlglents f line, the coupling of saidline with said looP "1 f to l S m being difierent for different positions of said within the spirit of the invention which is to bod y with respect to said station the amount gggigss gfi f only by the Scope of the of said coupling being determined by the What is claimedis: angle which the plane of said wires makes 1. In a system for communicating between with the Plane of Said P- a movin body and a plurality of terminal a system fer m h g between stations tween which it is moving, a'transa mevmg Vehlde and a P y of statlohs mission line connecting said stations adaptalong the route of Sale Vehlele, a twhsmls' ed to transmit signal variations impose S1011 h cqmrrlsmg a P h h y w P thereon, means on said noving Sal-d. IOllt to Stud StitlJlOIlS body inductively coupled with said line in are connected, conducting vImps Positlehed 60 which are indu d e t responsive t on said vehicle inductively coupled with said for changing the tr n f ffi i b t e traverses the distance between said stations,

said transmission means and said line from said variation being secured by gradupoint to point along the route of travel of ally rotating the plane of said wires in such th t itt d over id li d means line, said coupling being varied as the vehicle w the moving bod'y to provide a substantially a way that the loop associated with its re- 13 ing loops inductively 1 energy therebetween, and means for mission line spective terminal station has its osition of minimum coupling when the ve close proximity thereto and its In a system for communicating between the moving vehicle and a plurality of stations between which the vehicle is moving, a transmission line comprising a plurality of wires paralleling the route of said vehicle and connecting said stations, and individual conductcoupled with said line positioned on said vehicle and associated with each of said stations, the plane of said line with respect to the said loops being rotated from a position of maximum coupling with one of said loops and minimum coupling with another, at one station, to a position in which the respective degrees of coupling are reversed, at another station.

In a system for communicating between a moving vehicle and a plurality of stations between which the vehicle is moving, a trans mission line comprising a plurality of wires paralleling the route of said Vehicle and connecting said stations, a pair of conducting loops positioned at right angles to each other on said vehicle inductively coupled with said line, each of which is associated with a respective terminal station for intercommunication therewith, the coupling of said line with said loops being varied as the vehicle moves from one of said stations to the other by rotating the plane of said line wires from a p0sition of perpendicularity with the loop associated with the station from which it is about to'leave to a position of parallelism with the same loop upon reaching the other station.

9. In a system for intercommunicating between a vehicle and a plurality of stations situated at intervals along its route, a transmission line comprising a pair of wires running adjacent the route of said vehicle, transmission means aboard said vehicle inductively related to said transmission line to pror vide for the reciprocaltransfer of signaling providing constant attenuation of the signals received at said stations and aboard said vehicle, regardless of its motion between said stations, comprising provisions for producing gradual inclination of the plane of said transmission line with respect to said transmission means at an angle determinedby the position of the vehicle with respect to said stations.

10. In a system for intercommunicating between a vehicle and a plurality of stations situ'ated at intervals along its route, a transcomprising a pair of wires runmug-adjacent the route of said vehicle, transmission means aboard said vehicle comprising a plurality of conducting loopsinductively related to said line, sending and receiving apparatu's connected to said line at said stations icle is in maximum coupling at a point remote'therefrom tween the line and the other transmission of signals therebetween, and means for providing constant attenuation of the signals received bysaid receiving a paratus irrespective of the position of sai vehicle with respect to said stations, said means comprising said pair of line wires the plane of which is rotated with respect to' the planes of said loops to increase the efiiciency of energy transfer between the line and one of said loops as increasing distance between one station and the available for transfer along said line, and to decrease the efficiency of energy transfer beof said loops as the decreasing distance between the vehicle and the other of said stations increases the energy available for transfenalong said line.

In a system for communicating between a moving body anda terminal station, transmission means on said moving body and at said terminal station, respectively, a transmission line connected to said station and inductively coupled with said transmission means located on said body, the plane of said line with respect to said lattertransmission means being a function of the distance of the moving body from said station.

In witness whereof, I hereunto subscribe my name this 21st day of November, 1928. JOSEPH W. HORTON.

. and to said loops aboard said vehicle for the vehicle decreases the energy. 

